samedi 11 mars 2017

This animation shows the amount of light detected by each pixel in a small section of the camera onboard NASA's Kepler space telescope. The light collected from TRAPPIST-1, an ultra-cool dwarf star approximately 40 light-years from Earth, is at the center of the image. Not directly visible in the movie are the seven Earth-size planets that orbit TRAPPIST-1.

Kepler detects a change in brightness when a planet passes in front of a star from the vantage point of the telescope. Transiting planets block a tiny fraction of starlight that produces miniscule dips in the brightness of their host star. An Earth-size planet passing in front of a small ultra-cool dwarf star like TRAPPIST-1 creates less than a one percent dip in brightness, and is not visible with the naked eye.

Kepler Space Telescope. Image Credits: NASA/JPL-Caltech

Astronomers use sophisticated algorithms to search the data for these dips in brightness, and in particular, to correct for the spacecraft’s small movements in space—this is the 'flickering' of the pixels seen in the movie.

During the period of Dec. 15, 2016 and March 4, the Kepler spacecraft, operating as the K2 mission, observed TRAPPIST-1 for 74 days. This animation shows 60 brightness measurements or photos taken by Kepler's onboard camera once a minute for an hour on February 22. Called a target pixel file, the image covers an area of 11 square pixels or 44 square arcseconds of the sky. This area is equivalent in size to holding up a grain of sand at arms length towards the sky.

vendredi 10 mars 2017

NASA is preparing for longer human journeys deeper into space and is exploring how to keep astronauts healthy and productive. The Expedition 50 crew members today studied space nutrition, measured their bodies and checked their eyes to learn how to adapt to living in space. The space residents also unloaded a cargo ship, worked on the Tranquility module and practiced an emergency simulation.

The ongoing Energy experiment that ESA astronaut Thomas Pesquet collected urine samples for today seeks to define the energy requirements necessary to keep an astronaut successful during a space mission. Pesquet also joined NASA astronaut Peggy Whitson for body measurements to learn how microgravity affects body shape and impacts crew suit sizing. Commander Shane Kimbrough checked his eyes today with Whitson’s help and support from experts on the ground.

Kimbrough worked throughout the day before his eye checks and configured the Tranquility module for upcoming electronics and communications work. Cosmonaut Oleg Novitskiy continued unloading gear from the newly-arrived Progress 66 cargo ship. At the end of the day, Novitskiy joined Whitson and Pesquet for an emergency simulation with inputs from control centers in Houston and Moscow.

Image above: The Russian Academy of Sciences’ Space Research Institute (IKI) Venera-D mission concept includes a Venus orbiter that would operate for up to three years, and a lander designed to survive the incredibly harsh conditions a spacecraft would encounter on Venus’ surface for a few hours. Image Credits: NASA/JPL-Caltech.

A team of NASA-sponsored scientists will meet with the Russian Academy of Sciences’ Space Research Institute (IKI) next week to continue work on a Joint Science Definition Team study focused on identifying shared science objectives for Venus exploration. The visit comes after a report was recently delivered to both NASA Headquarters in Washington and IKI in Moscow, assessing and refining the science objectives of the IKI Venera-D (Venera-Dolgozhivuschaya) Mission to Venus, Earth’s closest planetary neighbor.

“While Venus is known as our ‘sister planet,’ we have much to learn, including whether it may have once had oceans and harbored life,” said Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington. “By understanding the processes at work at Venus and Mars, we will have a more complete picture about how terrestrial planets evolve over time and obtain insight into the Earth’s past, present and future.”

Venus has intrigued scientists for decades. Similar to Earth in composition and size, it spins slowly in the opposite direction. The rocky world’s thick atmosphere traps heat in a runaway greenhouse effect, making it the warmest planet in our solar system with surface temperatures hot enough to melt lead. Glimpses below the clouds reveal volcanoes and an intricate landscape. Venus is named for the Roman goddess of love and beauty, the counterpart to the Greek goddess Aphrodite.

First Flyby of Another Planet

“On a solar-system scale, Earth and Venus are very close together and of similar size and makeup,” said David Senske, co-chair of the U.S. Venera-D science definition team, and a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “Among the goals that we would like to see if we can accomplish with such a potential partnership is to understand how Venus’ climate operates so as to understand the mechanism that has given rise to the rampant greenhouse effect we see today.”

The IKI Venera-D mission concept as it stands today would include a Venus orbiter that would operate for up to three years, and a lander designed to survive the incredibly harsh conditions a spacecraft would encounter on Venus’ surface for a few hours. The science definition team is also assessing the potential of flying a solar-powered airship in Venus’ upper atmosphere. The independent flying vehicle could be released from the Venera-D lander, enter the atmosphere, and independently explore Venus’ atmosphere for up to three months.

NASA first visited Venus when the JPL-managed Mariner 2 collected data during a flyby in December 1962. NASA’s last dedicated mission to explore Venus was Magellan. Launched in 1990, and managed by JPL, Magellan used radar to map 98 percent of the planet at a resolution of 330 feet (100 meters) or better during its four-year mission.

The Venera spacecraft program is the only one to date to successfully land on Venus and survive its harsh environment. Said Adriana Ocampo, who leads the Joint Science Definition Team at NASA Headquarters in Washington, “This potential collaboration makes for an enriching partnership to maximize the science results from Venera-D, and continue the exploration of this key planet in our solar system.”

This beautiful Hubble image reveals a young super star cluster known as Westerlund 1, only 15,000 light-years away in our Milky Way neighborhood, yet home to one of the largest stars ever discovered.

Stars are classified according to their spectral type, surface temperature, and luminosity. While studying and classifying the cluster’s constituent stars, astronomers discovered that Westerlund 1 is home to an enormous star. Originally named Westerlund 1-26, this monster star is a red supergiant (although sometimes classified as a hypergiant) with a radius over 1,500 times that of our sun. If Westerlund 1-26 were placed where our sun is in our solar system, it would extend out beyond the orbit of Jupiter.

Hubble orbiting Earth

Most of Westerlund 1’s stars are thought to have formed in the same burst of activity, meaning that they have similar ages and compositions. The cluster is relatively young in astronomical terms —at around three million years old it is a baby compared to our own sun, which is some 4.6 billion years old.

NASA's upcoming mission to investigate the habitability of Jupiter's icy moon Europa now has a formal name: Europa Clipper.

The moniker harkens back to the clipper ships that sailed across the oceans of Earth in the 19th century. Clipper ships were streamlined, three-masted sailing vessels renowned for their grace and swiftness. These ships rapidly shuttled tea and other goods back and forth across the Atlantic Ocean and around the globe.

In the grand tradition of these classic ships, the Europa Clipper spacecraft would sail past Europa at a rapid cadence, as frequently as every two weeks, providing many opportunities to investigate the moon up close. The prime mission plan includes 40 to 45 flybys, during which the spacecraft would image the moon's icy surface at high resolution and investigate its composition and the structure of its interior and icy shell.

Image above: The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. Image credits: NASA/JPL-Caltech/SETI Institute.

Europa has long been a high priority for exploration because it holds a salty liquid water ocean beneath its icy crust. The ultimate aim of Europa Clipper is to determine if Europa is habitable, possessing all three of the ingredients necessary for life: liquid water, chemical ingredients, and energy sources sufficient to enable biology.

"During each orbit, the spacecraft spends only a short time within the challenging radiation environment near Europa. It speeds past, gathers a huge amount of science data, then sails on out of there," said Robert Pappalardo, Europa Clipper project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

Previously, when the mission was still in the conceptual phase, it was sometimes informally called Europa Clipper, but NASA has now adopted that name as the formal title for the mission.

The mission is being planned for launch in the 2020s, arriving in the Jupiter system after a journey of several years.

JPL manages the mission for the agency's Science Mission Directorate in Washington.

jeudi 9 mars 2017

Image above: DSS-14 is NASA's 70-meter (230-foot) antenna located at the Goldstone Deep Space Communications Complex in California. It is known as the “Mars Antenna” as it was first to receive signals from the first spacecraft to closely observe Mars, Mariner 4, on March 18, 1966. Image Credits: NASA/JPL-Caltech.

Finding derelict spacecraft and space debris in Earth’s orbit can be a technological challenge. Detecting these objects in orbit around Earth’s moon is even more difficult. Optical telescopes are unable to search for small objects hidden in the bright glare of the moon. However, a new technological application of interplanetary radar pioneered by scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, has successfully located spacecraft orbiting the moon -- one active, and one dormant. This new technique could assist planners of future moon missions.

“We have been able to detect NASA’s Lunar Reconnaissance Orbiter [LRO] and the Indian Space Research Organization’s Chandrayaan-1 spacecraft in lunar orbit with ground-based radar,” said Marina Brozović, a radar scientist at JPL and principal investigator for the test project. “Finding LRO was relatively easy, as we were working with the mission’s navigators and had precise orbit data where it was located. Finding India’s Chandrayaan-1 required a bit more detective work because the last contact with the spacecraft was in August of 2009.”

Add to the mix that the Chandrayaan-1 spacecraft is very small, a cube about five feet (1.5 meters) on each side -- about half the size of a smart car. Although the interplanetary radar has been used to observe small asteroids several million miles from Earth, researchers were not certain that an object of this smaller size as far away as the moon could be detected, even with the world’s most powerful radars. Chandrayaan-1 proved the perfect target for demonstrating the capability of this technique.

Image above: This computer generated image depicts the Chandrayaan-1’s location at time it was detected by the Goldstone Solar System radar on July 2, 2016. In the graphic the 120-mile (200-kilometer) wide purple circle represents the width of the Goldstone radar beam at lunar distance. The radar beam was pointed 103 miles (165 kilometers) off the lunar surface. The white box in the upper-right corner of the animation depicts the strength of echo. As the spacecraft entered and exited the radar beam (purple circle), the echo from the spacecraft alternated between being very strong and very weak, as the radar beam scattered from the flat metal surfaces. Once the spacecraft flew outside the beam, the echo was gone. Image Credits: NASA/JPL-Caltech.

While they all use microwaves, not all radar transmitters are created equal. The average police radar gun has an operational range of about one mile, while air traffic control radar goes to about 60 miles. To find a spacecraft 237,000 miles (380,000 kilometers) away, JPL’s team used NASA's 70-meter (230-foot) antenna at NASA's Goldstone Deep Space Communications Complex in California to send out a powerful beam of microwaves directed toward the moon. Then the radar echoes bounced back from lunar orbit were received by the 100-meter (330-foot) Green Bank Telescope in West Virginia.

Finding a derelict spacecraft at lunar distance that has not been tracked for years is tricky because the moon is riddled with mascons (regions with higher-than-average gravitational pull) that can dramatically affect a spacecraft’s orbit over time, and even cause it to have crashed into the moon. JPL’s orbital calculations indicated that Chandrayaan-1 is still circling some 124 miles (200 kilometers) above the lunar surface, but it was generally considered “lost.”

However, with Chandrayaan-1, the radar team utilized the fact that this spacecraft is in polar orbit around the moon, so it would always cross above the lunar poles on each orbit. So, on July 2, 2016, the team pointed Goldstone and Green Bank at a location about 100 miles (160 kilometers) above the moon’s north pole and waited to see if the lost spacecraft crossed the radar beam. Chandrayaan-1 was predicted to complete one orbit around the moon every two hours and 8 minutes. Something that had a radar signature of a small spacecraft did cross the beam twice during four hours of observations, and the timings between detections matched the time it would take Chandrayaan-1 to complete one orbit and return to the same position above the moon’s pole.

Image above: Radar imagery acquired of the Chandrayaan-1 spacecraft as it flew over the moon’s south pole on July 3, 2016. The imagery was acquired using NASA's 70-meter (230-foot) antenna at the Goldstone Deep Space Communications Complex in California. This is one of four detections of Chandrayaan-1 from that day. Image Credits: NASA/JPL-Caltech.

The team used data from the return signal to estimate its velocity and the distance to the target. This information was then used to update the orbital predictions for Chandrayaan-1.

“It turns out that we needed to shift the location of Chandrayaan-1 by about 180 degrees, or half a cycle from the old orbital estimates from 2009,” said Ryan Park, the manager of JPL’s Solar System Dynamics group, who delivered the new orbit back to the radar team. “But otherwise, Chandrayaan-1’s orbit still had the shape and alignment that we expected.”

Radar echoes from the spacecraft were obtained seven more times over three months and are in perfect agreement with the new orbital predictions. Some of the follow-up observations were done with the Arecibo Observatory in Puerto Rico, which has the most powerful astronomical radar system on Earth. Arecibo is operated by the National Science Foundation with funding from NASA’s Planetary Defense Coordination Office for the radar capability.

Chandrayaan-1 spacecraft. Image Credit: ISRO

Hunting down LRO and rediscovering Chandrayaan-1 have provided the start for a unique new capability. Working together, the large radar antennas at Goldstone, Arecibo and Green Bank demonstrated that they can detect and track even small spacecraft in lunar orbit. Ground-based radars could possibly play a part in future robotic and human missions to the moon, both for a collisional hazard assessment tool and as a safety mechanism for spacecraft that encounter navigation or communication issues.

JPL manages and operates NASA's Deep Space Network, including the Goldstone Solar System Radar, and hosts the Center for Near-Earth Object Studies for NASA's Near-Earth Object Observations Program, an element of the Planetary Defense Coordination Office within the agency's Science Mission Directorate.

More information about asteroids and near-Earth objects can be found at:

A regional dust storm currently swelling on Mars follows unusually closely on one that blossomed less than two weeks earlier and is now dissipating, as seen in daily global weather monitoring by NASA's Mars Reconnaissance Orbiter.

Images from the orbiter's wide-angle Mars Color Imager (MARCI) show each storm growing in the Acidalia area of northern Mars, then blowing southward and exploding to sizes bigger than the United States after reaching the southern hemisphere.

That development path is a common pattern for generating regional dust storms during spring and summer in Mars' southern hemisphere, where it is now mid-summer.

Animation above: This movie clip shows a global map of Mars with atmospheric changes from Feb. 18, 2017, through March 6, 2017, a period when two regional-scale dust storms appeared. It combines hundreds of images from the Mars Color Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter. Animation Credits: NASA/JPL-Caltech/MSSS.

"What's unusual is we're seeing a second one so soon after the first one," said Mars meteorologist Bruce Cantor of Malin Space Science Systems, San Diego, which built and operates MARCI. "We've had orbiters watching weather patterns on Mars continuously for nearly two decades now, and many patterns are getting predictable, but just when we think we have Mars figured out, it throws us another surprise."

Weather updates from the Mars Reconnaissance Orbiter science team provide operators of Mars rovers advance notice both for taking precautions and for planning observations of storms, particularly in case a regional storm grows to encircle the whole planet. A planet-encircling Martian storm last occurred in 2007.

The orbiter monitors storms with its Mars Climate Sounder (MCS) instrument as well as with MARCI. MCS measurements of high-altitude atmospheric warming associated with dust storms have revealed an annual pattern in the occurrence of large regional storms, and the first of these back-to-back storms fits into the identified pattern for this time of the Martian year.

Image above: This false-color scene from the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity documents movement of dust as a regional dust storm approached the rover's location on Feb. 24, 2017, during the 4,653rd Martian day, or sol, of the rover's work on Mars. Image Credits: NASA/JPL-Caltech/Cornell/ASU.

Researchers have watched effects of the latest storms closely. "We hope for a chance to learn more about how dust storms become global, if that were to happen," said David Kass of NASA's Jet Propulsion Laboratory, Pasadena, California. "Even if it does not become a global storm, the temperature effects due to thin dust hazes will last for several weeks."

Cantor reported the second of the current back-to-back regional storms on March 5 to the team operating NASA's Mars Exploration Rover Opportunity. The earlier storm, which had become regional in late February, was dissipating by then but still causing high-altitude haziness and warming.

"There's still a chance the second one could become a planet-encircling storm, but it's unlikely because we're getting so late in the season," Cantor said this week. All previously observed planet-encircling dust storms on Mars occurred earlier in the southern summer.

Opportunity Project Manager John Callas, at JPL, credits MARCI weather reports with helping his team protect rovers when sudden increases in atmospheric dust decrease sunlight reaching the rover solar arrays. For example, Cantor's warning about a regional storm approaching the rover Spirit in November 2008 prompted JPL to send an emergency weekend command to conserve energy by deleting a planned radio transmission by Spirit. That saved enough charge in Spirit's batteries to prevent "what would likely have been a very serious situation," Callas said.

Mars Reconnaissance Orbiter (MRO). Image Credits: NASA/JPL-Caltech

During the most recent global dust storm on Mars, in 2007, both of the rovers then operating on the planet -- Spirit and Opportunity -- were put into a power-saving mode for more than a week with minimal communication. The early-2010 ending of Spirit's mission was not related to a dust storm.

The same winds that raise Martian dust into the atmosphere can clear some of the dust that accumulates on the rovers. On Feb. 25, as the first back-to-back was spreading regionally, Opportunity experienced a significant cleaning of its solar panels that increased their energy output by more than 10 percent, adjusted for the clarity of the atmosphere. Dust-removing events typically clean the panels by only one or two percent. The Opportunity operations team has noticed over the years that a large dust-cleaning event often precedes dusty skies. Since Feb. 25, the atmosphere over Opportunity has become dustier, and some of the dust has already fallen back onto the solar panels.

"Before the first regional dust storm, the solar panels were cleaner than they were during the last four Martian summers, so the panels generated more energy," said JPL rover-power engineer Jennifer Herman. "It remains to be seen whether the outcome of these storms will be a cleaner or dirtier Opportunity. We have seen both results from dust storms in the past."

NASA's Curiosity rover, on Mars since 2012, uses a radioisotope thermoelectric generator for power instead of solar panels, so it doesn't face the same hazard from dust storms as Opportunity does. The possibility of observing the growth and life cycle of a regional or global storm offers a research opportunity for both missions, though. Scientists temporarily modified Curiosity's weather-monitoring regime last week in response to learning that a regional dust storm was growing.

"We'll keep studying this for weeks as the dust clears from the sky," said atmospheric scientist Mark Lemmon of Texas A&M University, College Station. Sky observations at multiple lighting angles can provide information about changes in the size distribution of suspended dust particles as additional dust is lifted into the sky and larger particles drop more quickly than smaller ones.

(Highlights: Week of Feb. 27, 2017) - Crew members on the International Space Station began activation of more than a dozen science investigations, including one that will examine lightning strikes on Earth from space.

The Lightning Imaging Sensor (LIS) is part of a suite of investigations on the Space Test Program-H5 delivered to the station by the 10th SpaceX resupply mission to the space station. This space-based lightning detector can locate lightning over a large area of the planet, providing real-time data and capturing images in higher latitudes than previously studied. The LIS measures the amount, rate and energy of lightning strikes. Lightning can help scientists study climate change because the storms that produce lightning are sensitive to small changes in temperature and atmospheric conditions. Improved understanding of lightning and its connections to weather provides crucial insight for weather forecasting, hurricane intensity, atmospheric chemistry and physics as well as aircraft and spacecraft safety, especially over oceans.

Image above: NASA astronaut Peggy Whitson works in the Microgravity Science Glovebox on the International Space Station, preparing microscope observations for the Microgravity Expanded Stem Cells investigation which cultivates human stem cells on the station for potential use in treating disease. Image Credit: NASA.

NASA astronaut Shane Kimbrough changed the filter on the Long Duration Sorbent Testbed (LDST) which scientists are using to create a more efficient life support system for long-duration, crewed space missions. A silica gel is currently used on the space station to remove humidity or water from the air, which allows life support hardware to more efficiently filter carbon dioxide from the air, making it breathable. These filters on the station need water removed from the air so carbon dioxide can be more easily processed along with waste hydrogen from the oxygen generator, converting two waste products into water, a precious commodity in space.

After a year, that silica gel loses up to 75 percent of its capacity to absorb water, making it necessary to replace it frequently. This investigation is studying 12 potential replacements for the gel to determine which would be most effective for use on long-duration missions. Data from the study will help determine the best material to use to build better filters, which would reduce the number of replacements sent on deep-space missions, leaving more cargo space available for other payloads. Ground crews will conduct a similar experiment in a laboratory on Earth using the same materials for comparison.

Image above: Scientists are using the Long Duration Sorbent Testbed on the International Space Station to investigate new methods to improve the life support systems on spacecraft for long-duration space missions. Image Credit: NASA.

ESA (European Space Agency) astronaut Thomas Pesquet started a multi-day investigation for the Astronaut's Energy Requirements for Long-Term Space Flight (Energy) study. He logged his dietary intake while wearing an armband that monitored his activities. Data from the ESA investigation will help mission planners send the correct amount of the right types of food with travelers into deep space. Pesquet is one of nine astronauts to be examined during exercise and rest cycles three months before launch, three months after arriving at the space station and adapting to the environment, and after returning to Earth.

Physicians are measuring metabolic rates, urine content and bone density to determine energy needs. Knowing details of astronaut metabolism and activity, combined with other conditions, will help ensure that crews are properly nourished on long missions. On Earth, extended bed rest due to age or illness has some parallels to a proper energy balance. Improved understanding from space missions will help in assessing patient needs on Earth.

Progress was made on other investigations, outreach activities, and facilities this week, including APEX-4, Microgravity Expanded Stem Cells, Rodent Research-4, ISS Ham Radio, Group Combustion, and NanoRacks Module-40.

For the supermassive black hole at the center of our Milky Way galaxy, it's been a long time between dinners. NASA's Hubble Space Telescope has found that the black hole ate its last big meal about 6 million years ago, when it consumed a large clump of infalling gas. After the meal, the engorged black hole burped out a colossal bubble of gas weighing the equivalent of millions of suns, which now billows above and below our galaxy's center.

The immense structures, dubbed the Fermi Bubbles, were first discovered in 2010 by NASA's Fermi Gamma-ray Space Telescope. But recent Hubble observations of the northern bubble have helped astronomers determine a more accurate age for the bubbles and how they came to be.

Image above: The light of several distant quasars pierces the northern half of the Fermi Bubbles - an outflow of gas expelled by our Milky Way galaxy's hefty black hole. Bottom left: the measurement of gas moving toward and away from Earth, indicating the material is traveling at a high velocity. Hubble also observed light from quasars that passed outside the northern bubble. Upper right: the gas in one such quasar's light path is not moving toward or away from Earth. This gas is in the disk of the Milky Way and does not share the same characteristics as the material probed inside the bubble. Image Credits: NASA, ESA, and Z. Levy (STScI).

"For the first time, we have traced the motion of cool gas throughout one of the bubbles, which allowed us to map the velocity of the gas and calculate when the bubbles formed," said lead researcher Rongmon Bordoloi of the Massachusetts Institute of Technology in Cambridge. "What we find is that a very strong, energetic event happened 6 million to 9 million years ago. It may have been a cloud of gas flowing into the black hole, which fired off jets of matter, forming the twin lobes of hot gas seen in X-ray and gamma-ray observations. Ever since then, the black hole has just been eating snacks."

The new study is a follow-on to previous Hubble observations that placed the age of the bubbles at 2 million years old.

A black hole is a dense, compact region of space with a gravitational field so intense that neither matter nor light can escape. The supermassive black hole at the center of our galaxy has compressed the mass of 4.5 million sun-like stars into a very small region of space.

Material that gets too close to a black hole is caught in its powerful gravity and swirls around the compact powerhouse until it eventually falls in. Some of the matter, however, gets so hot it escapes along the black hole's spin axis, creating an outflow that extends far above and below the plane of a galaxy.

Image above: Several distant quasars can be seen through the northern half of the Fermi Bubbles, an outflow of gas expelled by our Milky Way galaxy's hefty black hole. The Hubble Space Telescope probed the quasars' light for information on the speed of the gas and whether the gas is moving toward or away from Earth. Based on the material's speed, the research team estimated that the bubbles formed from an energetic event between 6 million and 9 million years ago. Image Credits: NASA, ESA, and Z. Levy (STScI).

The team's conclusions are based on observations by Hubble's Cosmic Origins Spectrograph (COS), which analyzed ultraviolet light from 47 distant quasars. Quasars are bright cores of distant active galaxies.

Imprinted on the quasars' light as it passes through the Milky Way bubble is information about the speed, composition, and temperature of the gas inside the expanding bubble.

The COS observations measured the temperature of the gas in the bubble at approximately 17,700 degrees Fahrenheit. Even at those sizzling temperatures, this gas is much cooler than most of the super-hot gas in the outflow, which is 18 million degrees Fahrenheit, seen in gamma rays. The cooler gas seen by COS could be interstellar gas from our galaxy's disk that is being swept up and entrained into the super-hot outflow. COS also identified silicon and carbon as two of the elements being swept up in the gaseous cloud. These common elements are found in most galaxies and represent the fossil remnants of stellar evolution.

The cool gas is racing through the bubble at 2 million miles per hour. By mapping the motion of the gas throughout the structure, the astronomers estimated that the minimum mass of the entrained cool gas in both bubbles is equivalent to 2 million suns. The edge of the northern bubble extends 23,000 light-years above the galaxy.

"We have traced the outflows of other galaxies, but we have never been able to actually map the motion of the gas," Bordoloi said. "The only reason we could do it here is because we are inside the Milky Way. This vantage point gives us a front-row seat to map out the kinematic structure of the Milky Way outflow."

The new COS observations build and expand on the findings of a 2015 Hubble study by the same team, in which astronomers analyzed the light from one quasar that pierced the base of the bubble.

"The Hubble data open a whole new window on the Fermi Bubbles," said study co-author Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland. "Before, we knew how big they were and how much radiation they emitted; now we know how fast they are moving and which chemical elements they contain. That's an important step forward."

The Hubble study also provides an independent verification of the bubbles and their origin, as detected by X-ray and gamma-ray observations.

Hubble and the sunrise over Earth

"This observation would be almost impossible to do from the ground because you need ultraviolet spectroscopy to detect the fingerprints of these elements, which can only be done from space," Bordoloi said. "Only with COS do you have the wavelength coverage, the sensitivity, and the spectral resolution coverage to make this observation."

The Hubble results appeared in the January 10, 2017, edition of The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Every day, invisible magnetic explosions are happening around Earth, on the surface of the sun and across the universe. These explosions, known as magnetic reconnection, occur when magnetic field lines cross, releasing stored magnetic energy. Such explosions are a key way that clouds of charged particles — plasmas — are accelerated throughout the universe. In Earth’s magnetosphere — the giant magnetic bubble surrounding our planet — these magnetic reconnections can fling charged particles toward Earth, triggering auroras.

Magnetic reconnection, in addition to pushing around clouds of plasma, converts some magnetic energy into heat, which has an effect on just how much energy is left over to move the particles through space. A recent study used observations of magnetic reconnection from NASA's ARTEMIS — Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun — to show that in the long tail of the nighttime magnetosphere, extending away from Earth and the sun, most of the energy is converted into heat. This means that the exhaust flows — the jets of particles released by reconnection — have less energy available to accelerate charged particles than previously thought.

When magnetic reconnection occurs between two clouds of plasma that have the same density, the exhaust flow is wildly unstable — flapping about like a garden hose with too much water pressure. However, the new results find that, in the event observed, if the plasmas have different densities, the exhaust is stable and will eject a constant, smooth jet. These differences in density are caused by the interplay of the solar wind — the constant stream of charged particles from the sun — and the interplanetary magnetic field that stretches across the solar system.

These new results are key to understanding how magnetic reconnection can send particles zooming toward Earth, where they can initiate auroras and cause space weather. Such information also provides fundamental information about what drives movement in space throughout the universe, far beyond the near-Earth space we can observe more easily.

ARTEMIS spacecrafts. Image Credit: NASA

The ARTEMIS spacecraft have now spent more than a decade investigating the invisible phenomena near Earth, working in tandem with other missions like Time History of Events and Macroscale Interactions during Substorms, and Magnetospheric Multiscale to form a complete picture of magnetic reconnection near Earth.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado. Caltech in Pasadena manages JPL for NASA.

mercredi 8 mars 2017

The crew is harvesting plants today grown on the International Space Station that will be returned to Earth aboard the SpaceX Dragon. Also, a variety of student experiments submitted from schools across the United States were activated inside the orbital laboratory.

Dragon is due to return to Earth and splash down in the Pacific Ocean March 19. The resupply ship will carry back gear and science samples for analysis by NASA personnel. Plants that were grown on petri plates for the APEX-04 study will also be returned aboard Dragon. Astronaut Peggy Whitson harvested those plants today helping researchers study the molecular changes that plants experience when grown in space.

Future scientists had their experiments activated today inside the NanoRacks commercial space research facility aboard the station. Students from five U.S. schools will be exploring ways to reduce infections, improve muscle injury treatments, grow plants on Mars, filter bacteria and solve common slippery surface problems.

Image above: The bright spots in the center of Occator Crater on Ceres are shown in enhanced color in this view from NASA's Dawn spacecraft. Image Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI/LPI.

The bright central area of Ceres' Occator Crater, known as Cerealia Facula, is approximately 30 million years younger than the crater in which it lies, according to a new study in the Astronomical Journal. Scientists used data from NASA's Dawn spacecraft to analyze Occator's central dome in detail, concluding that this intriguing bright feature on the dwarf planet is only about 4 million years old -- quite recent in terms of geological history.

Researchers led by Andreas Nathues at the Max Planck Institute for Solar System Research (MPS) in Gottingen, Germany, analyzed data from two instruments on board NASA's Dawn spacecraft: the framing camera, and the visible and infrared mapping spectrometer.

The new study supports earlier interpretations from the Dawn team that this reflective material -- comprising the brightest area on all of Ceres -- is made of carbonate salts, although it did not confirm a particular type of carbonate previously identified. The secondary, smaller bright areas of Occator, called Vinalia Faculae, are comprised of a mixture of carbonates and dark material, the study authors wrote.

New evidence also suggests that Occator's bright dome likely rose in a process that took place over a long period of time, rather than forming in a single event. They believe the initial trigger was the impact that dug out the crater itself, causing briny liquid to rise closer to the surface. Water and dissolved gases, such as carbon dioxide and methane, came up and created a vent system. These rising gases also could have forced carbonate-rich materials to ascend toward the surface. During this period, the bright material would have erupted through fractures, eventually forming the dome that we see today.

The spacecraft is currently on its way to a high-altitude orbit of 12,400 miles (20,000 kilometers), and to a different orbital plane. In late spring, Dawn will view Ceres in "opposition," with the sun directly behind the spacecraft. By measuring details of the brightness of the salt deposits in this new geometry, scientists may gain even more insights into these captivating bright areas.

Dawn spacecraft at Ceres. Image Credit: NASA/JPL-Caltech

The Dawn mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://dawn.jpl.nasa.gov/mission

On Feb. 22, astronomers announced that the ultra-cool dwarf star, TRAPPIST-1, hosts a total of seven Earth-size planets that are likely rocky, a discovery made by NASA's Spitzer Space Telescope in combination with ground-based telescopes. NASA's planet-hunting Kepler space telescope also has been observing this star since December 2016. Today these additional data about TRAPPIST-1 from Kepler are available to the scientific community.

During the period of Dec. 15, 2016 to March 4, the Kepler spacecraft, operating as the K2 mission, collected data on the star's minuscule changes in brightness due to transiting planets. These additional observations are expected to allow astronomers to refine the previous measurements of six planets, pin down the orbital period and mass of the seventh and farthest planet, TRAPPIST-1h, and learn more about the magnetic activity of the host star.

TRAPPIST-1h system

"Scientists and enthusiasts around the world are invested in learning everything they can about these Earth-size worlds," said Geert Barentsen, K2 research scientist at NASA's Ames Research Center at Moffett Field, California. "Providing the K2 raw data as quickly as possible was a priority to give investigators an early look so they could best define their follow-up research plans. We're thrilled that this will also allow the public to witness the process of discovery."

The release of the raw, uncalibrated data collected will aid astronomers in preparing proposals due this month to use telescopes on Earth next winter to further investigate TRAPPIST-1. By late May, the routine processing of the data will be completed and the fully calibrated data will be made available at the public archive.

The observation period, known as K2 Campaign 12, provides 74 days of monitoring. This is the longest, nearly continuous set of observations of TRAPPIST-1 yet, and provides researchers with an opportunity to further study the gravitational interaction between the seven planets, and search for planets that may remain undiscovered in the system.

TRAPPIST-1 wasn't always on the radar to study. In fact, the initial coordinates for the patch of sky defined as Campaign 12 were set in Oct. 2015. That was before the planets orbiting TRAPPIST-1 were known to exist, so Kepler would have just missed the region of space that is home to this newfound star system of interest.

But in May 2016, when the discovery of three of TRAPPIST-1's planets was first announced, the teams at NASA and Ball Aerospace quickly reworked the calculations and rewrote and tested the commands that would be programmed into the spacecraft's operating system to make a slight pointing adjustment for Campaign 12. By Oct. 2016, Kepler was ready and waiting to begin the study of our intriguing neighbor in the constellation Aquarius.

Kepler Space Telescope

"We were lucky that the K2 mission was able to observe TRAPPIST-1. The observing field for Campaign 12 was set when the discovery of the first planets orbiting TRAPPIST-1 was announced, and the science community had already submitted proposals for specific targets of interest in that field," said Michael Haas, science office director for the Kepler and K2 missions at Ames. "The unexpected opportunity to further study the TRAPPIST-1 system was quickly recognized and the agility of the K2 team and science community prevailed once again."

The added refinements to the previous measurements of the known planets and any additional planets that may be discovered in the K2 data will help astronomers plan for follow-up studies of the neighboring TRAPPIST-1 worlds using NASA's upcoming James Webb Space Telescope.

During Campaign 12, a cosmic ray event reset the spacecraft's onboard software causing a five-day break in science data collection. The benign event is the fourth occurrence of cosmic ray susceptibility since launch in March 2009. The spacecraft remains healthy and is operating nominally.

Ames manages the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Astronomers have used ALMA to detect a huge mass of glowing stardust in a galaxy seen when the Universe was only four percent of its present age. This galaxy was observed shortly after its formation and is the most distant galaxy in which dust has been detected. This observation is also the most distant detection of oxygen in the Universe. These new results provide brand-new insights into the birth and explosive deaths of the very first stars.

An international team of astronomers, led by Nicolas Laporte of University College London, have used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe A2744_YD4, the youngest and most remote galaxy ever seen by ALMA. They were surprised to find that this youthful galaxy contained an abundance of interstellar dust — dust formed by the deaths of an earlier generation of stars.

Follow-up observations using the X-shooter instrument on ESO’s Very Large Telescope confirmed the enormous distance to A2744_YD4. The galaxy appears to us as it was when the Universe was only 600 million years old, during the period when the first stars and galaxies were forming [1].

“Not only is A2744_YD4 the most distant galaxy yet observed by ALMA,” comments Nicolas Laporte, “but the detection of so much dust indicates early supernovae must have already polluted this galaxy.”

Cosmic dust is mainly composed of silicon, carbon and aluminium, in grains as small as a millionth of a centimetre across. The chemical elements in these grains are forged inside stars and are scattered across the cosmos when the stars die, most spectacularly in supernova explosions, the final fate of short-lived, massive stars. Today, this dust is plentiful and is a key building block in the formation of stars, planets and complex molecules; but in the early Universe — before the first generations of stars died out — it was scarce.

Artist’s impression of dust formation by supernovae in A2744_YD4

The observations of the dusty galaxy A2744_YD4 were made possible because this galaxy lies behind a massive galaxy cluster called Abell 2744 [2]. Because of a phenomenon called gravitational lensing, the cluster acted like a giant cosmic “telescope” to magnify the more distant A2744_YD4 by about 1.8 times, allowing the team to peer far back into the early Universe.

The ALMA observations also detected the glowing emission of ionised oxygen from A2744_YD4. This is the most distant, and hence earliest, detection of oxygen in the Universe, surpassing another ALMA result from 2016.

The detection of dust in the early Universe provides new information on when the first supernovae exploded and hence the time when the first hot stars bathed the Universe in light. Determining the timing of this “cosmic dawn” is one of the holy grails of modern astronomy, and it can be indirectly probed through the study of early interstellar dust.

Zooming in on the young dusty galaxy A2744_YD4

The team estimates that A2744_YD4 contained an amount of dust equivalent to 6 million times the mass of our Sun, while the galaxy’s total stellar mass — the mass of all its stars — was 2 billion times the mass of our Sun. The team also measured the rate of star formation in A2744_YD4 and found that stars are forming at a rate of 20 solar masses per year — compared to just one solar mass per year in the Milky Way [3].

“This rate is not unusual for such a distant galaxy, but it does shed light on how quickly the dust in A2744_YD4 formed,” explains Richard Ellis (ESO and University College London), a co-author of the study. “Remarkably, the required time is only about 200 million years — so we are witnessing this galaxy shortly after its formation.”

This means that significant star formation began approximately 200 million years before the epoch at which the galaxy is being observed. This provides a great opportunity for ALMA to help study the era when the first stars and galaxies “switched on” — the earliest epoch yet probed. Our Sun, our planet and our existence are the products — 13 billion years later — of this first generation of stars. By studying their formation, lives and deaths, we are exploring our origins.

“With ALMA, the prospects for performing deeper and more extensive observations of similar galaxies at these early times are very promising,” says Ellis.

And Laporte concludes: “Further measurements of this kind offer the exciting prospect of tracing early star formation and the creation of the heavier chemical elements even further back into the early Universe.”

Notes:

[1] This time corresponds to a redshift of z=8.38, during the epoch of reionisation.

[2] Abell 2744 is a massive object, lying 3.5 billion light-years away (redshift 0.308), that is thought to be the result of four smaller galaxy clusters colliding. It has been nicknamed Pandora’s Cluster because of the many strange and different phenomena that were unleashed by the huge collision that occurred over a period of about 350 million years. The galaxies only make up five percent of the cluster’s mass, while dark matter makes up seventy-five percent, providing the massive gravitational influence necessary to bend and magnify the light of background galaxies. The remaining twenty percent of the total mass is thought to be in the form of hot gas.

[3] This rate means that the total mass of the stars formed every year is equivalent to 20 times the mass of the Sun.

More information:

This research was presented in a paper entitled “Dust in the Reionization Era: ALMA Observations of a z =8.38 Gravitationally-Lensed Galaxy” by Laporte et al., to appear in The Astrophysical Journal Letters.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

mardi 7 mars 2017

After a two-month stay aboard the International Space Station, NASA’s Technology Educational Satellite (TechEdSat-5) that launched Dec. 9, 2016, was deployed on March 6, 2017 from the NanoRacks platform and into low-Earth orbit to demonstrate a critical technology that may allow safe return of science payloads to Earth from space.

Orbiting about 250 miles above Earth, the Exo-Brake, a tension-based, flexible braking device resembling a cross-shaped parachute, opens from the rear of the small satellite to increase the drag. This de-orbit device tests a hybrid system of mechanical struts and flexible cord with a control system that warps the Exo-Brake. This allows engineers to guide the spacecraft to a desired entry point without the use of fuel, enabling accurate landing for future payload return missions.

Small Satellite With Exo-Brake Technology Launches From International Space Station

Two additional technologies will be demonstrated on TechEdSat-5. These include the ‘Cricket’ Wireless Sensor Module, which provides a unique wireless network for multiple wireless sensors, providing real time data for TechEdSat-5.

The project team seeks to develop building blocks for larger scale systems that might enable future small or nanosatellite missions to reach the surface of Mars and other planetary bodies in the solar system.

Viscous, lobate flow features are commonly found at the bases of slopes in the mid-latitudes of Mars, and are often associated with gullies.

These features are bound by ridges that resemble terrestrial moraines, suggesting that these deposits are ice-rich, or may have been ice-rich in the past. The source of the ice is unclear, but there is some thought that it is deposited from the atmosphere during periods of high obliquity, also known as axial tilt.

The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.9 centimeters (10.2 inches) per pixel (with 1 x 1 binning); objects on the order of 82 centimeters (32.2 inches) across are resolved.] North is up.